Method of and means for protecting combustibles



Aug. 4 1936. w. J. WILLENBORG METHOD OF AND MEANS FOR PROTECTINGCOMBUSTIBLES Filed Jan. 15, 1950 3Sheets-Sheet, 1

I um/n h d/fer f hW/mfioy Aug. 4, 1936. I w. J. WILLENBORG 2,049,987

METHOD OF MEANS-FOR PROTECTING CQMBUSTIBLES Filed Jan. 13, 1950 :sSheets-Sheet? awuwtoz ll d/ /ir i v [VJ/c0507 936. w. J. 'WlLLENBORG2,049,987

' METHOD OF AND MEANS FOR PROTECTING COMBUSTIBLES. I

' 'Fild Jan. 13, 1950 s Shets-Sheet :5-

anoemtoz ,Patented Aug. 4, 1936 rras . ms'rnon or" arm man's ron PRO-rncriuc coMBUs'rmLEs Walterii. Wilienborg, Weehawken, N. 5., assignor toUnited States Fire Protection Corporation, l-ioboken, N. J., acorporation of Delaware Application January 13, 1930, Serial No. 420,613

15 Claims. (01'. 230-85) mable gases;' it is the object of thisinvention to provide protective means for the spaces ,in whichcombustibles are kept.

An important object of my invention is to provide and maintain, inspaces in which combustibles are kept, an atmosphere in which suchcombustibles, or gases given off thereby, cannot be infiarned or burned.

Another object is to devise means by which the so-called inertatmosphere in .spaces which serve for the storage of combustibles iskept substantially at atmospheric pressure, so that the walls of saidspaces are not exposed to excessive strains. Giving to the walls of suchspaces sufficientstrength to withstand the pressure of the atmoshere onthe outside, in case the atmosphere in said spaces is rarefied, or towithstandan excessive pressure of the "inert gases-contained therein,would represent a considerable economical burden, particularly becausesuch spaces are frequently very large.

1 Another important reason for preserving the inert" atmosphere in suchspaces at a pressure substantially equal to that of the atmospheresurrounding said spaces is the object of preventing the leakage of theinert gases contained therein through cracks or openings 'in the wallsmaking up said spaces, or, to prevent the difiusion of the outside airthrough such cracks-or openings into the inert atmosphere which ismaintained on the inside .of such spaces.

A further object of this invention is to maintain the inert atmospherein a space, in which combustibles are contained, at a standard of safetywhich experience has proven to oflera fully satisfactory protection andautomatically to raise said standard of safety in case the requirementsof protection are increased, when inflammable gases are given off by thecombustibles in said space.

It is another object of my invention to provide compensation for thefluctuation of the amount of inert gases contained at substantiallyatmospheric pressure in such spaces, such I fluctuation being caused byan increase or de-' must frequently be accorded to the spaces where suchmeans and machinery are operated, be-

cause mechanical friction and electric sparks, which are difficult toavoid in the operation of such means and machinery, must be protectedagainst, in order to prevent, ignition and explosion of the surroundingatmosphere. I have devised regulation for the atmosphere in the spacesin which such means and machinery are kept, which affords a protectionagainst such ignition or explosion and which'at the same time permitsthe entrance of a person into the respective spaces for the purpose ofmanually opcrating such means or machinery in the case of an emergency.

Another, important object of my invention is to provide for theprotection of the inside of the. tanks of a tanker, which are known tocorrode and deteriorate at an extraordinary rate under the combined andalternating influences of salt water, air, oil and oil-vapors. -Suchde-- terioration is effectively prevented by my invention in which theatmosphere in the tanks is largely rendered inert.

In view of these and other objects I have developed the method and meansdescribed below, and; have exemplarily chosen for an illustration of myinvention a prominent field of its application, which is tankers usedfor the overseatransportation of inflammable liquids, such as oil,petroleum or gasoline. Such tankers and the means whichI use in theapplication of my protection to such tankers are illustrated in theaccompanying drawings, in which,-

Figure .1 is a side elevation of part of a tanker.

Figure 2 is a corresponding plan view of the tanker.

Figure 3 shows a schematic top view of the arrangement of pipes, pumpand control means in the shaft.

Figure 4 is a corresponding part of the "shaft.

Figure 5 is the side elevation of the forepart of a vessel showing amodification of my invention.

Figure 6 shows a diagram view of the vapor indicator and the apparatuscontrolled thereby.

Figure 7 shows a partly sectioned side View of the breathing means.Similar numerals refer to similar parts throughout the various views.

, The tanker shown in Figures 1 and 2 is laid along the lines of presentday practice of constructing vessels of this type. The engine andboilerrooms are arranged in the stern of thevessel and the power plantcomprises a generator which supplies steam or electricity for theopera-- side elevation of tion of the motive parts, primarily pumps,used in connection with my improvements; the bow is used for freight,and quarters for the crew whereas the tanks containing the liquid cargoare arranged therebetween and are ordinarily separated from the fore andaft parts of the vessel by protective coffers. Two vertical shafts I3and M, which are normally open at their upper ends extend down from themain deck to substantially the keel; in their lower ends I5 are arrangedthe oil pumps which serve to pump the oil out of the vessel. Two pairsof main tanks l6 and I1 are arranged aft each of the shafts I3 and I4and correspondingly two pairs of tanks I8 and I9 are arranged forethereof.- Alongside of the tanks I0, II, I8 and I9 are indicated thewing tanks I0 which may be protected by my improvements in a mannercorresponding to the hereinafter described protection of thefirst-mentioned tanks.

The various tanks are ordinarily filled with oil or gasoline.l2, a smallclearance being allowed between the surface of the liquid and the topwalls of said tanks, which are represented by the main deck. Theseclearances allow for. the expansion and contraction of the liquid underdif-- :in the tanks above the liquid, if the tanks were hermeticallysealed, and the walls of the-tanks would thereby be exposed todangerously high and low pressures. For this reason so-called breathersare ordinarily provided, which, througha trap-like arrangement, connectthe gas filled space above the liquid in the tank to the outside andthrough which the pressures above the liquids phere.

in the tanks may be balanced against the atmos- Through such breathersair is taken in when, at sunset, the contracting contents of the tankstend to create a vacuum thereabove; whereas gas is driven out throughthe breathers, when the temperature rises in the morning.

-In my invention the unidirectional valves 20 take the place of thebreathers. They permit the excess pressure of gas above the liquid inthe tanks to be relieved therethrough, but they do not allow air fromthe outside to enter into the space above the tanks at night, when thetemperature drops and a vacuum is created above the liquid, but Iprovide in that case other means for restoring the low gas pressureabove the liquid to a normal pressure, which is slightly aboveatmospheric pressure. v

The unidirectional valves maybe constructed according to the simpleprinciples of a safety valve; they may take the shapes of traps, theliquid in which allows the passage of gas therethrough in one but not inthe other direction or they may take the shape of one of the manydevices which provides for unidirectional sensitive gas pressurecontrol. To the unidirectional valves are connected the pipe lines 2|extending to the sides of the ship and their outlets 22 issue overboard,below the'level of the main deck.

A detailed illustration of a particular modification of the breathingapparatus is shown in'Figto those acquainted with the art of valvesears.

I sea.

The checking operationin the. valve body is brought about by the plungerIOI which operatively connects a diaphragmin the diaphragm chamber I02to the shut off means in the valve body proper. The valve connects bymeans of the pipe I03 to the space above the liquid in the tanker and anauxiliary. pipe I04 by-passes a small amount of the gas coming from thetank into the diaphragm chamber. In the diaphragm chamber the diaphragmis raised and lowered I06 and a screen I01 which extends across thewhole horizontal extent of said chamber I06. Flash-arresters of thiskind are used in the line through which, surplus gas is released fromthe pump room, as well as throughout the apparatus of my inventionwherever pipe lines issuing from one or the other tank are merged or areconnected to a common header. If for any unforeseeable reason aninflammable gas mixture is contained in one or more of the tanks, suchflash-arresters prevent the propagation. of .an explosion, which mayoccur in one of said tanks, to the other tanks. Below theflash-arrester, above the outlet of the breatherv line, thepipe showsanother enlarged chamber-I00 in which a hollow ball I09 is supported,from-below, by brackets IIO. Chamber I08 is of such size as to allow afree passage of the gases breathed out from the tanks around said ball.I09. The contracted lower end of the pipe prevents splashing .of waterthereinto and the ball I09 is buoyed and blocks the neck III of chamberI00, when'the lower end of the breather pipe line is submerged underwater in a rough 7 Near the center of thebody arises above the main deckan inert gas Igenerating plant 23 in which, by means of an internalcombustion engine 24, gases are produced which are commonly termed inegases. These inert gases are the exhaust gases of the engine 24 and aretermed inert" gases because they are non-oxidizing, inasmuch as theyprevent the combustion of inflammable materials therein, unless suchinflammable materials contain the oxygen required for their combustion.The exhaust gases of the engines 24 are purified and cleaned inscrubbers 25 and then they are stored in high pressure tanks 20. Thesehigh pressure tanks are connected by pipe lines 28 to a reducing valveboard 21 from where pipe lines 29 connect into the shafts l3 and I4. Thereducing valves are set to maintain the gas in pipe lines 20 at apressure which assures a free flow of said gases to the points of use ofsuch gas, when required. The gas for the operation of engines 24 issupplied from an auxiliary gasoline. tank 30. This gasoline tank and thepipe line 3| connecting said tank to the engines are protected andjacketed with inert gas manings sealed by heavy glass covers 33. Thesepump rooms are filled with an inert atmosphere, means for maintainingsuch an atmosphere being more specifically discussed below. At times,when it becomes necessary to enter this chamber, air 7 is admitted, sothat the breathing of a person entering the pump. room is not impaired;at the same time an explosion-proof condition of the atmosphere in thepump room may be maintained. it being known that the-oxygen in a roommay be reduced to such an extent, that it will not permit ignition ofinflammable materials, said atmosphere not causing to a person enteringthereinto any serious discomfort excepts slight shortness of breath.

On deck 32 in the pump room I install the apparatus by which I protectthe inflammable-liquids contained in the various tanks I6, II, It andi0.

' The equipment in each of the shafts i3 and I4,

into lines at and 55 which issue into the respecr I tive pairs oi portand starboard tanks below the main deck and above the top level of theliquid. 4 The suction lines 38, 31, 08, 49 and 50 connect, as returnlines, the tanks 10, II, It and i9 and the pump'rooms E5 to the blowers34, 05, 30, 31 and 38. .In the manner of the branches 44 and 40 issuingfrom the discharge lines 38,-40, 4|, and 62 into the various tanks l8,l1, l8 and [9, the

suction lines 66, $1, $8 and 49 are branched oil at their ends by lines5| and'52.- The pipe, lines El and '52 issue upon the opposite ends ofthe spaces above the liquids in each of the port and starboard tanks. I

The discharge lines are provided with check valves 53 at points near theblowers and, ahead of these valves, small pipe lines 50 branch oi! andlead to the vapor indicators 05. Behind the check valves the pipe lines56 issue thereinto. Those pipe lines 56 connect to the solenoidal valves51 which in turn connect to a manifold 58 to which 13 and i i.

inert gas reduced to a predetermined pressure is supplied from thereducingvalve boa-rd 2'! of the inert" gas generating plant by pipe line29. The solenoidal valves connect to the manifold M by the pipe lines59, 80, 6t, 62 and, 63, which, respectively, belong to the systems ofthe blowers '38,

M, 31, 36 and 3b.

The operation of the vapor indicators and of the solenoidal valves maybest be seen from the diagram of Figure 6; an unbalanced Wheatstonebridge M is connected by means of wires 65 and 66. across the source 67-of a' constant E. M. E. One pair of arms of the bridge are formed by-thefixed resistances 6t and 69, whereas the other pair of arms contain theresistance wires of-the thermal conductivity units I0 and .H. The gal--vanometer F2 is connected across the bridge as an indicating instrumentby'means of the wires Thermal conductivity unit I0 is bridged by asuitable resistance wire and it contains a comparison gas, whereas thethermal conductivity unit H which is equipped with a similar resistancewire is connected at the inlet 15 to the small pipe line 54 throughwhich gas is supplied for analysis from the blowers.

, The galvanometer is empirically calibrated, I

showing a-scale fromzeroto 100 which may be defined as a percentagescale for inertness of the gas analyzed. The divisions are arra ged insuch a manner that a-de-flection of 50 is registered by the galvanometerwhen air mixed with just enough inert gas so as not to sustain freecombustion passes through the conductivity unit H, whereas the 100%point of the scale is registered, when the'best possible "inert" gasproduced by the generating plant 23 is introduced in the thermalconductivity unit ll.

Exemplarily I choose thecalibration point 50' of the-scale for thequality which is to be main- I tained in the gas above the liquid. inthe tanks.

. I exemplarily allow 15% upward and downward marginal limits for thatstandard; therefore I l0 have provided means that a supplyofsubstantially. fully inert" gas which has been delivered by thegenerating plant is admitted through the pipe line 56 into the dischargeof the blower,

when theinertness indicator registers per- 15 cent but I shut oil thissupply of inert gas when the inertness" is indicated to have risen to65%. Simple means to bring about such a control of thesupply of inertgas by means of thevapor indicator are shown in Figure 6; the hand I6 ofthe 20 galvanometer 12 carries a brush 11 near its point-- ed end whichis adapted to contact electrically with the segments 18 and 19, wheneither an inertness .from zero to 35% or from 65% to 100% is registered.Electricity is supplied to the 20 hand by means of wire 80 and it flowsfrom the galvanometer through wires BI and 82 to relays 03 and, when thebrush 11 on hand 16 contacts with the segments l8 and |9 respectively. Areturn wire 85 closes the electric circuit and it also supplieselectricity to the magnet lever 86, which will swing to the right or tothe left according to whether relay 03 or relay M is excited.

Whereas the various pieces of electrical apparatus are shown to besupplied with current from 35 a common source ti, they may of course besupplied from difierent sources of current, each one oi'which isparticularly suited for the respective current requirements; or thevarious electrical devices such as the analysis units, the solenoidalvalves, the relays, and the apparatus used collaterally in thegalvanometer operation may be floated on the line oi'the ship'selectrical power supply.

The diagrammatic drawing of Figure 6 illus-- trates the principle uponwhich the vapor indicator controls the -inert gas supply. In a practicalapplication the hand 18 oithe galvanometer is of course not used forcarrying currents, nor do which I may choose the one best. adapted forthe problems of a particular installation. The circuit closing contactdoes not have to be brought about directly by the handf'lt, but thepresent state of the art ofiers'many instniments in which such a contactis indirectly brought about and instruments in which periodically, atshort and regular intervals ai time, mechanical means automatically feel,out or test theposition of a pointer and accordingly close or openrelay circuits. and which may readily be substituted for the apparatusdiagrammatically shown in the drawings. I U I The lever 06 is, retainedin its positions o1' at'- traction to one or theother oi the relays bythe wedge-shaped nose extending from an upwardly tensioned catch 81,said wedge-shaped nose engaging the right or left side of the lowerpointed end of the lever 86 in the extreme positions of deflection ofsaid lever. When the lever 86 is attracted by relay 06, it closes thecircuit .94 of the solenoidai valve 51 at the pointof contact 88,

which circuit inthe drawing is connected across the source .61 ofelectric power. The solenoidal valve 51 is normally open, so that itallows inert" gas to be supplied from the generating plant to thedischarge lines of the respective blowers, when the solenoid isnotexcited. i

The lever 86 being swung to the right in the drawing and the solenoidcircuit 94 therefore being open, the solenoidal valve is open. But ifthe percentage of inertness registered by the galvanometer rises from 38to 65, contact of brush If the degree of "inertness of the gascirculating through the respective blowerdecreases slowlyuntil itreaches the low safe margin of 35%,

the brush 1! will contact with segment 18, the solenoid circuit isopened and the solenoidal valve opens, the degree of "inertness of thegas which moves from the respective blower through the respectivedischarge line being increased by the supply of fully inert gas fromthegenerating plant. The galvanometer will consecutively register ahigher degree of inertness until the upper margin of 65% has beenreached again, when the supply through the solenoidal valve is shuto'fi.

An alarm 90 is connected in parallel with relay 83. It may be taken outof the circuit by opening switch 9|. When switch 9! is closed the alarmwill be actuated whenever the inertness" of the gas circulating'throughthe respective blower is below the safe lower margin of 35%.

The arrangement of Figure shows the "inert gas generating plant locatedin an alternative position near the bow of the boat. From the reducingboard 21 of the generating plant the inert gas passes in thismodification to a main pipe line 92. Branches 95 of that pipe line runto each of the main tanks and to the pump room and arerespectively-controlled by the solenoidal valves 51. Small motor drivenpumps 93 are arranged near the unidirectional breathers 20 and theycontinuously supply a small amount of the gas to the vapor indicator 55.vWires connecting the vapor indicator 55 to the solenoidal valve 51 formpart of the solenoid circuit 94.

Whereas any kind of an inert" gas may be used to create a safeatmosphere in the various spaces in which combustibles are stored orhandled, the most economical gas used today for such purposes is theproperly cleaned exhaust gas of an internal combustion engine. Thearrangement of a generating plant for such gases has been described byme in Letters Patent No. 1,952,005, issued March 30th, 1934, entitled"Control for a producer of non-oxidizing gases and plants of this kindare indicated at 23 in Figures 1 and 2 near midship and in Figure 5 nearthe bow of a boat. Such a plant produces an exhaust gas, cleans it,tests it and automatically stores it in high pressure tanks 28. The highpressure tanks issue upon areducing valve board 21. The gas flows fromthe high pressure tank through the valves mounted on that board, andfrom there, at a reduced pressure,when the line pressure, at the pointof use, drops below a predetermined pressure standard, to which thereducing valve is set,-into the main distributing lines 29.

In theabove cited prior patent it has been stated that any reliableapparatus serving for the determination of the carbon dioxide contentsin a certain atmosphere may be satisfactory for checking the quality ofthe inert gas produced in the generating plant. Any such 'device, whichis adapted for registering the carbon dioxide contents of an atmosphere,may also be used in the vapor indicators 55 which serve to check thequality of the gases in the spaces above the liquids in the tanks aswell as the quality of the gas in the pump room i5. However, Iillustrate in' Figure 6 of my drawings an apparatus which seemsparticularly adapted for the purpose of protecting spaces to. which Ihave referred in my introduction. In addition to reacting upon andregistering the carbon dioxide contents of the atmosphere to be tested,this apparatus is also influenced by the inflammable gases which are aptto arise from the oil or gasoline stored in the various tanks of atanker.

In observing the thermal conductivity of gases the value of theconductivity of a gas is compared with air and the observed or computedratio is termed the factor of thermal conductivity of gas. The gasesprimarily coming into question for observation in considering theprotection of tanks in which hydrocarbons are stored are carbon dioxideand hydrogen. The thermal conductivity factor of carbon dioxide iscomparatively low and I have found that the protective quality of anexhaust gas is the greater, the larger the percentage of carbon dioxidecontained therein. Since carbon dioxide primarily influences the thermalconductivity test of an exhaust gas, the actual percentage of carbondioxide in an exhaust gas can be substantially directly observed andregistered on a galvanometer by means of a Wheatstone bridgearrangement, The procedure in and the apparatus used for making suchobservations is described in detail in Technologic Paper No. 249published by the Bureau of Standards of the Department of Commerce ofthe United States and a detailed description thereof will therefore notbe necessary. vThe comparison gas is accommodated in the thermalconductivity unit 10, whereas the gas to be tested passes through thethermal conductivity unit II. The latter is therefore connected to oneof the small pipe lines '|5 which issue from the discharge lines of thetanks and of the pump rooms. In the modification of Figure 5 the thermalconductivity unit H of the vapor conductivity 55 is connected to a smallpump 93 which withdraws a small sample of the gas contained above theinflammable liquid in the tank, from a corner opposite the corner atwhich the supply of "inert gas issues into said space through the pipe95. Whereas in the testing apparatus of my prior invention the testingor the exhaust gases only had to be considered and the dilution of saidgases with air was largely the determining factor for the percentage ofcarbon dioxide observed, in this new application of a'thermalconductivity unit for determining the quality of gases withdrawn fromthe space above hydrocarbons the gases volatilized from the hydrocarbonsmust also be considered in the reading registered, and hydrogen andother gases given oil. by inflammable liquids indeed exert a greatinfluence upon the'thermal conductivity of the atmosphere they arecontained in.

Hydrogen has a high factor of thermal conductivity and its influenceupon the reading observed is directly opposed to the deflection causedby carbon dioxide. The scale of the galvanometer 12 being empiricallydivided to register the quality of an inert gas from the center of the 7in a harbor and when there is substantially no scale which wouldcorrespond to' the thermal conductivity of air mixed with just enoughinert gas so as not to sustain free combustion, to a maximum inertnesswhich would correspond to the highest possible carbon dioxide contentsordinarily observed in exhaust gases, the introduction of hydrogen or ofgases which have similar thermal conductivity factors will tend to causethe deflection of the needle is in counterclockwise direction, so thatthe galvanometer will register less inertness inan inert atmos phere, assoon as hydrogen or similar inflammable gases are introduced into saidatmosphere. The galvanometer is arranged to operate the collateralapparatus so as to preserve an average inertness of 50%. Assuming thatthere is an average inertness of 50%, the inertness registered will fallbelow the 50 calibration as soon as inflammable gases enter upon thetherbeing automatically increased when inflammable gases are present.

The solenoidal valve 51 is shown enlarged in Figure 6 and the flow ofgas pressure is indicated to take place from the right to the left. Whenthe solenoid is excited the stem of the valve is lifted and the port'isclosed, the valve seating therein from below, so that the supply ofinert gas from the reducing valves, to the right, is shut ofl from thespaces above the liquids or from the pump room, to the left of saidvalve. The force with which the solenoid holds or retains the valve inits seat can be adjusted so that it is readily overcome by a certaindrop if the pressure from the right to the left in said valve. Thisallows the solenoidal valve to be also used as a check valve, "inert"gas being admitted to the spaces above the liquids in the tanks, or tothe gases circulating therethrough when the pressure drops below. acertain, fixed value. In a practical application of my invention Ipreferably use pressure control means which act independent of thequality-controlling.

solenoidal valves. Such means are not indicated in Figure 3,not toobscure the principle of the invention shown. But in Figure 4 a check orpressure regulating valve 20 is shown inserted between thepoint 91 ofline 40 and the line 63 connecting the corresponding solenoidal valve tothe manifold 58 and correspondingly the pipes v59, 50, Bi, and 62 may beconnected by check or pressure in the tanks rises above a predeterminedpressure in excess of normal atmospheric pressure, is removed from thedeck of the ship.-

Owing to its heaviness that gas will drop onto the water alongside ofthe ship and it therefore will not inconvenience the crew of .the shipmoving about on the deck. This featureis of particular importance whenthe ship is anchored wind to take away from the deck of the. ship gaseswhich may prove to be annoying.

The small pumps 93 of Figure 5 drive samples of the gas'contained in thetanks above the inflammable liquid, and gases contained in the pump roomnear the top thereof, into the vapor indicators 55 where their qualityof inertness is registered. Accordingto the quality registered, thesolenoid circuit of the solenoidal valve 51, to which the impulses ofclosingv and opening the relay circuits by means of the contactor H aretransmitted through the wires 94, will be operated. If the quality ofthe gas recorded is of insufiicient safety, the supply of gas from thereducing valve board 21 is supplied through the solenoidal valve intothe spaces above the inflammable liquids or into the pump room and sucha supplying of new inert gas will continue until the vapor indicator 55again registers a high degree of safety in the atmosphere in therespective spaces. The pressure of the gas supplied from the reducingvalve board slightly exceeds the pressure normally preserved in thespaces above the inflammable liquids and in the pump room and the valves20 are set to release at a pressure between that of the gas'suppliedfrom the reducing valve board and atmospheric pressure. The flow of"inert gas through the pipes 95 into the various spaces will thereforenot be prevented by a buildingup of pressure 'in the respective spaces,but the gas of inferior quality will be breathed out" of the spacesabove the inflammable liquids at the opposite ends. thereof, until asafe standard of inertness" has been reached in said spaces and thesupply of new inert" gas is shut off by the solenoidal valves- 51!.

If the pressure in the spaces above the liquids rises above the pressurenormally to be mainsucked in through the solenoidal valve in accordancewith the action described above, or it enters through a check valvearranged in parallel with the solenoidal valve 51. The releasing ofsurplus pressure .from the pump room is not indicated in the drawing bycheck valves, but

ings around the port holes 33 or through other crevices and cracks. Ifsuch releasing should operate reversedly, sucking air into said room,the inert standard of safety of the atmosphere would automatically berestored since the inferior quality of the gas, as'sampled in the vaporindicator 55, would bring about a supply of new inert gas to the pumproom from the reducing valve board. As an extreme measure of safety Imay of course provide check valves on the pump rooms, as I have shownthem in'connection with the'spaces abovethe inflammable liquids in thetanks. But such a measure will ordinarily not be necessary, because thegas in the pump room is not exposed to'the same amount of expansion andcontraction due to temperature diflerences, which occurs in the spacesabove the inflammable liquids in the tanks.

-Maintaining the gas in atank above an inflammable liquid at a fixeddegree of inertness or at zero intrinsic inflnmmability, instead ofproviding a may inert" zone therein and of coin- 7 I such releasing maytake place through the opensafety. It is also important from aneconomical point of view, because normally a very limited supply ofinert gas is required to maintain the quality of the protecting zone.The necessity of introducing additional gas arises in my improvementsprimarily, whenja replacement of a volume of gas, which has beenbreathed out" on account of expansion, has to be made.

The system of Figure 5 requires however the release of a certain amountof the atmosphere contained above the inflammable liquid, when safeinertness" is to be reimparted to said atmosphere. The gas thus releasedmay also contain vapors of the inflammable liquid and the inflammableliquid will automatically give off additional amounts of vapors until anormal saturation of the newly introduced inert gas has been attained. Apart of the most valuable ingredients of the inflammable liquid, i. e.,the parts which ordinarily have the highest'fiash-point are therebyremoved from the inflammable liquid.

The quality of the inflammable liquid is thus impaired and I havesucceeded in improving still further upon the system of Figure 5, by thesystem of Figures 1, 2, 3 and 4, in which substantially the same gasmakes up the atmosphere above the inflammable liquids in the tanks, saidgas being continuously circulated and restored to a pre-' determinedinert quality during such circulation. In the drawings I show a centralpoint at which the testing, controlling and circulating apparatus islocated, 1. e., in the shafts l3 and it, above deck'32. Of course thisarrangement and location of the apparatus may be modified in adaptationto the vessel or storage means, in connection with which it is used. Thechoice of the number of individual circulating systems shown has alsobeen arbitrary; in the same manner in which I provide one individualcirculating system for a pair of adjoining tanks, and in the manner inwhich I apply the circulating system to two adjoining tanks in aparallel arrangement, I may also use one system for a smaller or greaternumber of tanks and may connect the system to said tanks in a seriesarrangement. Likewise the protection provided for the tanks locatedalong a longitudinal center line of the vessel may be extended to thewing tanks l0.

Although the description of the apparatus, as given above, explains manyparts of the apparatus of Figures 1, 2, 3 and 4, I describe in thefollowing the circuit of one circulating system, in order to ascertainthe understanding of my invention: The pump 35 continuously withdrawsthe atmosphere contained in the pair oftanks II by means of the branches5| and 52 of pipe line 41; at the discharge end of pump 35 a sample ofthe gas is by passed through the small pipe line 54 at a pressure whichmaybe largely controlled by dimensioning the conductors. Check valves 53prevent a flow of the newly introduced gas in a direction opposite tothat in which circulation is caused by the pumps. The small pipe line 54introduces the by-passed gas into the thermal conductivity unit II andthe quality of the gas thus tested, as compared with the comparison gasin thermal conductivity unit III, is registered by the galvanometer 12.The electrical parts of Figure 6 operatively connect the galvanometer 12to the solenoidal valve S'Lwhich controls the supply of "ine gas frommanifoldfl through pipe lines 63 and 56 into the discharge line 40 ofstored in the tank culated back to the pair of tanks i1 and dis- Itributed thereinto by means of the branches H and 45 of pipe line 40.

When the pressure of the gas in tank ll above the inflammable liquidscontained therein drops owing to a; temperature drop, the valve 20between the point 91 of line 40 and the line 63 operates, or

' the solenoidal valve 51 connecting pipe line 63 to pipe line 56functions as a check valve, as described above, and a supply of inertgas suflicient to restore atmospheric pressure in the tanks ll passestherethrough; when that gas pressure rises above atmospheric pressurethe check valve 20 allows breathing out of the gas, overboard, untilsubstantially atmospheric pressure is rell. Of course the gas breathedout of the tanks may be stored in gasometers or pressure tanks, andrecirculated when pressure conditions in the storage spaces warrant it.I

The use of a circulating system of gas in connection with my inventionbrings about a great economy in the use of inert" gases and I therefoream in a position to provide comparatively small inert gas generatingplants in connection with large vessels. Such smaller gas generatingplants may not have a capacity sufficient to supply all the inert" gaswhich may be regasometers filled with inert" gas, which supply the bulkof the amount of inert gas required when the vessel is unloaded. Thevapor indicators on the vessel may function as protective means wheninert gas is admitted to the tanks from the gasometers arranged alongthe shore of the harbor. Insufficiency of quality of the gas suppliedfrom shore or leakage of the supply line and connections will beindicated on the galvanometer and an alarm is given by the alarm 90, foras long a period of time as the quality of the gases in the tank isbelow a standard of 35%. The alarm may of course also be used during theordinary operation of my invention to warn -the crew that the quality ofthe atmosphere in the testing method chosen allows a regular orcontinuous testing and the resulting registrations are adapted tocontrol and to' be operatively connected with the control valve gears.If the exhaust gas of the internal combustion engine is used, any of themany carbon dioxide analyzers known to the art today may be adopted fora measurement of inertness. v 7

One particular modification of the apparatus is, under certaincircumstances, of particular value for obtaining a high degree of safetyin protecting combustibles. My thermal conductivity method may becombined with a carbon dioxide analyzer, the two kinds of tests being 75i spanner v a from said tanks for its quality of sustaining comecarriedon'alongside of each other, .one serving to measure the general quality.of the atmosphere above the combustibles and registering therefor;

generally, the degree of danger of the mixed gases, the other testregistering the quality of inertness, only, of the atmosphere, withoutconsideration of the inflammable gases which are contained therein. Suchcompounding, tests and corresponding modification of the operation ofthe control valve suggests itself in particular for spaces in which theinertness cannot be carried toan extreme limit of safety but where the anecessity of occasional entrance of an operator has to be considered aSuch an arrangement could for applied tothe'pump room; the compoundedregistering means allow, differentially, a determination of theinflammable gases present and .under certain circumstances it may beadvisable for the operator to flush out the atmosphere in the pump dial,'as-shown, is exemplarly, only, and under varying conditions a higher orlower standard of safety may be adopted.

Although I have shown and described several specific form'sof embodimentof my invention in detail, -'yet I'do not wish to be limited therebyexcept as the state of the art and the .appfinded claims may require,for a large range ofemodiflcations and changes suggest themselves to theengineer and designer applying my invention to problems of protectingcombustibles, without thereby bringing about 'a departure from thespirit andsco'p'e of my invention.-

What I desire to patent is: 1 a v 1. The method of protectingcombustible liquids stored in tanks, comprising withdrawing from saidtanksgas contained "in said tanks above said liquids, analyzing the gaswithdrawn instance be bustion, registering said analysis, and injectinggas of inferior quality of sustaining combustion into said tanks abovesaid liquids, said injecting of gas being automaticallycontrolled bysaid registering of said analysis.

2. The method of protecting'combust'ible liquids stored" in tanks,comprising withdrawing from said tanks gas contained in said tanks abovesaid liquids, analyzing the gas withdrawn from said tanks forits'inflammability, registering said analysis, and infecting gas of lowquality of sustaining combustion into said tanks above said 1 liquids,said injecting of gas being automatically controlled by said registeringof said analysis.

' 3. 'The method of preserving a standard of inertness in, thejatmosphere contained in an en-' closure and admixed with combustiblegases,

comprising circulating said atmosphere in an endless circuit, observingthe degree of inflammability of said circulating atmosphere bycontinuously registering the proportionate amount of carbon dioxide andcombustible gases contained therein, and injecting inert gas into saidatmosphere in conformity with said observations.

4-. The method of preserving a. standard of inertness in the atmospherecontainedin an enclosure and admixed withcombustible gases, comprisingcirculating said atmosphere in an endless circuit, observing the degreeof infiammability of said circulating atmosphere by continuouslyregistering the thermal conductivity thereof, and injecting inert gasinto said atmosphere in conformity with said observations? 5. Means forproviding a protective gas zone 35 in an enclosure, comprising anendless pipe system through which the gas contained in said en-'closureis continuously circulated, means measuring the quality ofinertness of the zone of gas of said enclosure, a source of inert gas,and valve and'admitting said inert gas to said enclosure'in conformitywith said measurements.

.. WALTER J WILLENBORG.

. means connecting said source with said system, operatively connectedwith said measuring means

